TM 1-1510-218-10 3C-31 Table 3C-7. Heading Reference Indicator Values HEADING SWITCH SELECTION ACTIVE FREE / SLAVE SWITCH FREE / SLAVE SELECTION HEADING REFERENCE INDICATOR DISPLAYED All on Compass 1 Pilot Free DG1 (amber) Slave MAG1 (amber) All on Compass 2 Copilot Free DG2 (amber) Slave MAG2 (amber) Normal On-side Free DG (white) Slave Blank (26) Wind Pointer.The wind indicator consists of a green symbol located on the outside edge of the compass and graphically layered to not obscure the heading bug symbol, lubber line, or heading readout. The wind indicator rotates about the aircraft symbol such that the arrow is always pointing into the compass at the wind direction. The arrow displays zero to five green fins on its tail to represent wind speed. Long fins represent 10 knots and short fins represent 5 knots. If the wind velocity is 0 knots, the arrow is removed from the display. If the wind velocity is less than 2.5 knots, the arrow is displayed with no fins. The wind indicator indicates wind from .1 knots to 45.5 knots. If the wind exceeds 45.5 knots, the wind indicator changes to a maximum wind symbol (wind indicator with a filled triangle fin at the tail). When the wind speed or wind direction is invalid or unavailable, the wind indicator is removed from the display. (27) To/From Indicator.A white triangle to or from indicator rotates around the aircraft symbol on the course needle. It indicates TO the station when the triangle points towards the head of the course needle and FROM the station when the triangle points towards the tail of the course needle. If FMS is the selected course and FMS outputs a waypoint alert, the TO/ FROM flag flashes. If the course source is not FMS, the indicator is set to TO when the angular difference between the relative bearing to the station and the primary course is less than 89. When the angle is greater than 91FROM is indicated. The indicator is OFF when the angle is between 89 and 91. When FMS is the primary source then the FMS determines the TO/ FROM indication. If the TO/ FROM indication is invalid or unavailable, an active navaid has not been selected, or the indicator is OFF, the TO/ FROM flag will be removed from the display. (28) Miniature Aircraft. The white aircraft symbol is located in the center of the compass rose. f. EHSI Operations(1) OBS Backup Mode. When the heading is invalid, the compass rose rotates about the aircraft such that the selected course is always referenced at the top of the display. When the selected course is invalid, the compass freezes at the last known position. (2) Course Source Flag. When the navigation information for the selected course is flagged invalid, the course source label is removed from the display and replaced with the course source annunciation drawn in black on a solid red box. The deviation bars and scale are removed from the display with a navigation flag. If the primary course goes invalid, the selected course readout is replaced with red dashes. If FMS-800 or the KLN 90 is selected and an FMS NAV Warn occurs (RAIM Alert), the MS NAV source annunciator turns amber and all the navigation information remains on the display. (3) LOC/BC. If an LOC frequency has been tuned and backcourse is selected on the flight director, BC is displayed in place of the LOC source. Once BC has been set it will remain set as long as the BC discrete is set.g. HSI ARC Format. The compass arc format, Figure 3C-11, is a graphic representation of the current heading of the aircraft. It is similar to the compass rose, except that only an 80 slice is shown. The arc format is an expanded compass with the compass segment at the top of the display and the aircraft symbol centered laterally at the bottom. The compass rotates about the center point of the aircraft such that the current heading is indicated directly below the lubber line. The HSI format with the 360 compass rose display is the same as the HSI Arc display with the following exceptions.